The present invention relates to administration of a toxic agent to a subject with cancer, in a formulation in which toxicity is substantially reduced and/or therapeutic efficacy enhanced. The most widely used methods to treat cancer are surgery, radiation and chemotherapy. Cancer patients often receive a combination of these treatments and about half of all patients receive chemotherapy. Unfortunately, chemotherapeutic agents have significant limitations relating to their toxic effect on the patient and the efficacy of a particular dosage to target and kill tumor cells.